Effectiveness of a peroxy compound in whitening a dental surface can be enhanced in presence of a basifying agent, typically an alkaline compound such as a carbonate or bicarbonate salt, it being well known that release of oxygen from peroxy compounds such as hydrogen peroxide is promoted at higher pH. However, if a peroxy compound is formulated for storage in an alkaline medium, its effectiveness as a whitening agent can be reduced through premature release of oxygen.
Efforts to deliver to a dental surface a peroxy compound and a basifying agent to activate the peroxy compound have included simultaneous delivery of such agents in two-component products wherein the agents are kept separate until introduction to the mouth or shortly prior thereto.
For example, European Patent No. 0 897 714 discloses a two-component mouthwash product wherein one component comprises hydrogen peroxide in aqueous solution at pH<4.5 and the other a buffer salt in aqueous or aqueous/alcoholic solution at pH>8. The two components are mixed before use.
U.S. Pat. No. 5,928,628 to Pellico discloses a two-component bleaching system adapted for application to teeth from a dental bleaching tray. One component comprises a peroxide gel having a pH of about 4 to about 7 and the other an alkaline gel having a pH of about 9 to about 13. The two components are mixed before use.
U.S. Patent Application Publication No. 2002/0141949 of Banerjee & Friedman proposes applying a gel comprising a peroxide bleaching agent to a tooth surface using an applicator such as a brush having an activator (e.g., sodium carbonate or sodium bicarbonate) in a dry form stored therein.
In contrast to the above disclosures, U.S. Pat. No. 6,174,516 to Curtis et al. discloses a sequential treatment method, according to which there is first applied to teeth an aqueous rinse composition having an alkaline pH and thereafter the teeth are brushed with a peroxide dentifrice.
Patents and publications cited above are incorporated herein by reference.
There remains in the art a need for alternative methods for improving dental whitening activity of a peroxy compound by interaction thereof with a basifying agent.